Fluid control valves

ABSTRACT

A fluid control valve has a spool located in a bore for controlling the flow of fluid from an inlet pressure port to outlet ports depending on the position of the spool. In the embodiments described and illustrated a proportion of inlet fluid pressure is used to rotate the spool and to move the spool in the bore.

United States Patent [191 Browne FLUID CONTROL VALVES [75] 'lnventor:John Patrick Browne, Bletchley,

Bnckinghamshire, England [73] Assignee: Sandall Precision CompanyLimited, Bletchly, Buckinghamshire, England [22] Filed: Apr. 12, 1971[21] Appl No.: 133,152

[30] Foreign Application Priority Data Apr. 27, 1970 Great Britain20,083/70 [52] US. Cl 137/332, 91/3, 137/83, 137/468, 137/625.61,l37/625.63, 137/625.64

[51] Int. Cl. F15b 5/00, Fl6k 29/02 [58] Field of Search 137/331, 332,625.63, 137/625.64; 91/3, 430

v 1 References Cited UNITED STATES PATENTS 2,359,017 9/1944 Balsiger137/332 June 26, 1973 2,664,097 12/1953 Parker 137/332 2,896,654 7/1959Gnzmann 137/83 3,473,547 10/1969 Coakley 137/625.63 X 3,205,782 9/1965Tourtellotte 137/83 X Primary Examiner-Martin P. Schwadron AssistantExaminer-Richard Gerard Attorney-Larson, Taylor and Hinds [57] ABSTRACTA fluid control valve has a spool located in a bore for controlling theflow of fluid from an inlet pressure port to outlet ports depending onthe position of the spool. In the embodiments described and illustrateda proportion of inlet fluid pressure is used to rotate the spool and tomove the spool in the bore.

8 Claims, 15 Drawing Figures PATENTEDJUNZB ms SHEET t 0F 7 W @UK v TmPAIENIEDJUN 26 973 SHEET 6 OF 7 NTOE PATENTEU JUN 26 4915 SHEEI 7 OF 7Lsmq.

FLUID CONTROL VALVES This invention relates to fluid control valves, andmore particularly to such valves incorporating a spool for controllingfluid.

It is an object of the present invention to provide a fluid controlvalve capable of operation with a good reliability and a low thresholdin environmental conditions where the level of fluid contaminent may berelatively high.

It is a further object of the invention to provide such a valve in whichmaintenance requirements are at a minimum and servicing is a relativelysimple task.

According to the invention I provide a fluid control valve including aspool for controlling the flow of pressurised fluid from an inlet portto at least one outlet port, wherein a proportion of inlet fluidpressure is used to rotate the spool.

The inlet fluid pressure may also be used to cause longitudinal movementof the spool.

In another form of the invention I provide a fluid control valve havinga body, a sleeve fixedly secured in the body and a spool located in abore in the sleeve, a

chamber in the sleeve at each end of thespool, inlet and outlet ports inthe body communicating with ports in the sleeve and annular chambersformed between a plurality of heads on the spool, the heads beingarranged so that the axial position of the spool controls the flow offluid through the valve, wherein first means are provided forcontinuously rotating the spool when pressurized fluid is supplied tothe inlet port and second means are provided for varying fluid pressurebeing supplied to the chamber at each end of the spool.

The invention will now be described by way of example only withreference to the accompanying drawings, in which:

FIG. 1 is a part sectional view through a fluid control valve showingone embodiment of the invention,

FIG. 2 is a sectional view on lines A-A of FIG. 1 and lines 13-13 ofFIG. 6,

FIG. 3 is a sectional view on lines B--B of FIG. 1,

FIG. 4 is a non-sectional view of the area of the spool enclosed withinthe circle C on FIG. 1,

FIG. 5 is a view on arrow D of FIG. 4, FIG. 6 is a part sectional viewthrough a fluid control valve showing another embodiment of theinvention,

FIG. 7 is a sectional view on lines F-F of FIG. 6,

FIG. 8 is a non-sectional view of the area of the spool enclosed withinthe circle G on FIG. 6,

FIG. 9 is a view on arrow H of FIG. 8,

FIG. 10 is a sectional view on lines J.] of FIG. 6,

FIG. 11 is a sectional viewtaken on lines K-K of FIG. 10,

FIG. 12 is a sectional view showing a modification of the valve shown inFIGS. 1 and 6,

FIG. 13 is a part sectional view on lines LL of FIG. 12,

FIG. 14 is a graph to explain a particular feature with relation to FIG.13, and

FIG. 15 is a non-sectional view showing a further modification of thevalve shown in FIGS. 1 and 6.

Referring now to FIG. 1, a spool generally indicated at 11 having heads12, 13, 14, 15 and 16, is located in the bore of a sleeve 49 fixedlysecured in a valve body 17. Each end of the bore is sealed by a cap 50secured by bolts 51. Annular chambers 52, 53, 54 and 55 are formed onthe sleeve 49 and communicate through ports 56, 57, 58 and 59respectively with annular chambers 22, 25, 26 and 23 formed between theheads on the spool 11. The width of heads 13 and 15 is such that whenthe spool is in the neutral position as shown in FIG. 1 the meteringedges of the heads overlap the edges of two ports 60 and 61 sufficientto block the passage of fluid. The ports 60 and 61 communicate throughtwo annular chambers 62 with ports 18 and 19 respectively formed in thebody 17. Two ports 20 and 21 formed in the body 17 communicate withannular chambers 52 and 55 respectively. A pressure port 24 is connectedthrough a branch duct with annular chambers 53 and 54.

In the valve of FIG. 1, two orifices 27 extend into the head 14 from theend adjacent the chamber 25. The orifices 27 extend in a directioninitially substantially parallel with the longitudinal axis of the spoolto approximately half way through the head then through 90, insubstantially the same plane but in opposite directions, to communicatewith two chambers 28 formed around the centre of the head 14 and bestshown in FIGS. 3,

. 4 and 5. From FIG. 3 it will be seen that the orifices 27 are locatedin bosses 29 in the head 14 and communicate one to each of the twochambers 28. Reference to FIGS. 4 and 5 will show that the bosses 29extend between two heads 30 and 31 formed on the outer edges of head 14,the heads 30 and 31 serving to isolate the chambers 28 from the chambers25 and 26. The chambers 28 communicate through threeradially disposedorifices 32 with an annular chamber 33 formed in the sleeve 49 (FIG. 3).

A conduit 34 connects the chamber 33 through a pressure reducer 35 to ajet pipe assembly 36 which includes a static transfer jet 109 and adeflecting jet 37 suspended from a torque tube 38 and located in achamber 39 formed in the body 17. The chamber 39 is connected to a fluidreservoir (not shown). The deflecting jet 37 terminates in a jet nozzle110 and is offset laterally from the centre line of a splitter disc 40formed in the head 16 on the spool 11 (FIGS. 1 and 2). Two annularreceiving chambers 41 and 42 are formed one on each side of the splitterdisc 40.-Receiving chamber 41 communicates through an orifice 43 in thesplitter disc 40 and a bore 44 in one end of the spool with an actuatingchamber 45 formed between the cap 50 and the end surface of the spool11. Receiving chamber 42 communicates in a similar manner throughorifice 46 and bore 47 with an actuating chamber 48 formed between thesecond cap 50 and the opposite end of the spool 11.

The pressure reducer 35 in the valve of FIG. 1 is in the form of aseries of orifice plates.

The embodiment of the valve shown in FIG. 6 is similar to thatpreviously described except for a rearrangement of the ports on thespool and a modified pressure reducer, and similar elements have beengiven the same numbers with primes attached.

In the valve of FIG. 6, two orifices 27' extend into the head 14 fromthe end adjacent the chamber 25' at an angle to the longitudinal axis ofthe spool 11', then at in opposite directions to communicate with acontinuous annular chamber 63 formed in the head 14' and best shown inFIGS. 7, 8 and 9. The chamber 63 communicates through three radiallydisposed orifices 32' with an annular chamber 33' formed in the sleeve49' (FIGS. 6 and 7). A conduit 34' connects the chamber 33 through apressure reducer 35' to a jet pipe assembly 36. It will be apparent thatin this embodiment the splitter disc 40 and the two annular receivingchambers 41' and 42 are also located in the head 14' which is locatedcentrally of the spool 11. The pressure reducer 35' is in the form of aone-piece frustoconical unit shown in more detail in FIGS. and 11.

With reference to FIGS. 10 and 11, an inlet orifice 64 connects theupstream end of a tapered body 98 to an inlet chamber 65, which isconnected through a series of orifices 66 located in the walls ofchambers located circumferentially of the body 98 to an outlet chamber67. The outlet chamber 67 is connected via an orifice 68 to thedownstream side of the reducer 35'.

FIG. 12 shows details of a modification which can be incorporated intoeither of the valve arrangements previously described which provides apressure and temperature compensated reducer.

A sleeve 69 is fixedly secured in a bore 70 in the body 17. Acompensating spool 71 is slidably mounted in a bore in the sleeve 69 andis fixed at its upperend to an aluminium rod 72. The rod 72 extendsthrough a clearance bore in the spool 71 and is connected at its lowerend to a piston 73 slidably mounted in a bore 74 which is closed by acap 75. The bore 70 is closed by a cap 76. A coil spring 77 is locatedin a chamber 78 between the end of the first sleeve 69 and a disc 79which abuts the upper edge of the piston 73. Diametrically opposed ports80 formed in the sleeve 69 communicate with annular chambers 89 on thespool 71 of identical pitch to the ports 80. An inlet port 81 in thesleeve is connected by a passage 82 in the body 17 to the annularchamber 33 (FIG. 3) and 33 (FIG. 7), and an outlet port 83 is providedat the opposite end of the sleeve. Bore 74 is connected by a passage 84to the pressure port 24 and the chamber 78 is connected to a fluidreservoir (not shown). Orifices 85 are provided in the walls of thespool 71 and a flange 86 having orifices 87 is provided at its upper endand located in a chamber 88 formed in the bore 70 between the end of thefixed sleeve 69 and the cap 76. I

FIG. 12 also shows a modification of the jet pipe assembly previouslydescribed. Outlet port 83 communicates with a bore 90 formed in one endof a housing 91 rotatably positioned in a bore 92 in the body 17. Theother end of the housing is supported in the bore of a retainer 93secured in the body 17 by bolts 94. The bore 90 extends through an angleof 90 into a deflecting jet 95 formed on the housing and teminates inajet nozzle 110 located in a chamber 111 and positioned above a splitterdisc 40 formed on the spool 11 as previously described. The chamber 111is connected to a fluid reservoir (not shown). One end of a torque tube96 is fixed in the housing 91, the other end protruding through aretainer 97 for connecting to a suitable torque motor (not shown). Aprojection 99 is formed on the housing 91 diametrically opposite thedeflecting jet 95 and is located in a chamber formed between the wallsof the body 17 and the retainer 93. In FIG. 13 it will be-seen that dueto the mass of the projection 99 opposite the deflecting jet 95 thecentre of gravity 108 of the assembly is located above a pivot point107.

In FIG. a jet nozzle 100 is shown located above a splitter disc 101formed on a spool 106, in a similar manner to that previously described.In this embodiment, however, the edges 102 and 103 of two fluidreceiving chambers 104 and 105 are of complementary sinusoidal shape asopposed to the straight edges of the chambers in the embodiment of FIGS.1 and 6.

In operation of the valve shown in FIG. 1, pressurized fluid applied tothe pressure port 24 flows into the annular chambers 53 and 54 andthrough the ports 57 and 58 into the annular chambers 25 and 26. Thefluid passes into the orifices 27 and ejects into the chambers 28 (FIGS.1 and 3) or chamber 63 (FIGS. 6 and 7). In both cases this arrangementprovides, in effect, a balanced fluid jet motor in an isolated portionof the spool and provides energy to impart rotation to the spool 11within the bore of the sleeve 49.

Utilization of this energy reduces the pressure of the fluid which nowflows through the orifices 32, the annular chamber 33 and the conduit34, and is further reduced in the pressure reducer 35 to a levelsuitable for use in the jet pipe assembly 36.

The fluid flows through the deflecting jet 37 and issues from the jetnozzle to impinge on the edge of the splitter disc 40 (FIG. 2) so thatthe jet reaction force on the spool contributes an additional torque inthe same sense as the fluid jet motor.

When the nozzle 1 10 is directly above the edge of the splitter disc 40the fluid flows at equal pressures into each of the receiving chambers41 and 42 and through the orifice 43 of bore 44 and orifice 46 and bore47 respectively to the actuating chambers 45 and 48 located at eitherend of the spool, thus providing a positional servo-mechanism whichcontrols spool displacement. As shown in FIG. 1, with the jet nozzle 110issuing directly onto the edge of the splitter disc 40, the fluidpressures in actuating chambers 45 and 48 are equal and the spool iscontinuously rotated and maintained in the neutral position shown inFIG. 1 with the heads 13 and 15 blocking the ports 60 and 61, to preventany of the input fluid pressure in chambers 25 and 26 from flowingthrough annular chambers 62 to ports 18 and 19. Surplus fluid isreturned to a reservoir (not shown) through the chamber 39.

Displacement of the spool in the bore of the sleeve is accomplished asfollows. If it is desired to move the spool to the left as viewed inFIG. 1, the jet nozzle 110 of the deflecting jet 37is swung by thetorque tube 38 also to the left to cause more fluid to enter receivingchamber 42 than enters chamber 41, resulting in an increase of fluidpressure in actuating chamber 48. Excess fluid in actuating chamber 45exhausts through the bore 44, the orifice 43 and receiving chamber 41,to mix with surplus fluid returning to the reservoir through the chamber39. The increased fluid pressure in chamber 48 acts on the area of thespool 11 and results in the continuously rotating spool 11 beingdisplaced to the left in the bore of the sleeve 49. This movementuncovers ports 60 and 61 to allow a flow of fluid from the input fluidpressure in chamber 26 to the port 19, and also provides communicationbetween ports 18 and 20. Movement of the spool to the right as viewed inFIG.- 1 is accomplished in a similar manner by swinging the deflectingjet 37 to the right to increase the fluid flow into receiving chamber41, and therefore increasing the pressure in actuating chamber 45, anddecreasing the fluid flow into receiving chamber 42, which results in adecrease in fluid pressure in actuating chamber 48. Displacement of thespool 11 to the right from the position shown in FIG. 1 allows a flow offluid from the input fluid pressure in chamber 25 to the port 18, andalso provides communication between ports 19 and 21.

In one application the valve of the present invention may form part of ahydraulic system in which the pressure port 24 is connected to a sourceof high pressure fluid, for instance, oil pumped from a reservoir. Ports20 and 21 are connected to the reservoir, and ports 18 and 19 areconnected to a reversible hydraulic motor which could be of either thereciprocating or rotating type. Axial displacement of the spool,therefore, provides variable area orifices between heads 13 and andports 60 and 61 respectively, to control direction, pressure and/orvolume of fluid flowing from the pressure port 24 to the motor througheither of the ports 18 or 19. The area of the orifices is determined bythe displacement of the spool from the neutral position, thisdisplacement being a function of the differential pressure in actuatingchambers 45 and 48 which is proportional to movement of the deflectingjet 37 from its neutral position.

The valve of FIG. 6 operates in a similar manner to that previouslydescribed. Inlet fluid pressure is ejected from the orifices 27' intothe chamber 63 (FIGS. 6, 7, 8 and 9) to impart continuous rotation tothe spool 11' in the sleeve 49. The fluid flows through the orifices32', the annular chamber 33' and the conduit 34', and is further reducedin the pressure reducer 35' to a level suitable for use in the jet pipeassembly 36'.

In the valve of FIG. 1 the fluid flowing through the series of orificeplates in the pressure reducer 35 reduces the pressure to a suitablelevel for use in the jet pipe assembly. In the valve of FIG. 6 the fluidenters the tapered body 98 of the pressure reducer 35' through the inletorifice 64 (FIGS. 10 and 11) to an inlet chamber 65. The fluid flowsthrough the series of orifices 66 to an outlet chamber 67, then throughthe orifice 68 at suitably reduced pressure to the jet pipe assembly36'. The force necessary for operating the torque tube 38 (FIG. 1) or 96(FIG. 12) may be derived from any suitable source and may, for instance,be in the form of a torque motor. The motor may be operated from amechanical, fluidic, hydraulic, electric or electromagnetic source.

One set of typical valve operating pressures may be as follows: system(inlet) pressure 3,000 p.s.i.; outlet pressure from fluid jet motor2,600 p.s.i.; outlet from pressure reducer 200 p.s.i.

In a system where the fluid temperature is controlled and the systempressure supply is sensibly constant, then either of the pressurereducer arrangements previously described will be more than adequate tomaintain a relatively constant fluid pressure to the jet pipeassemblies. However, as the magnitude of the fluid pressure in theactuating chambers at either end of the spool is a proportion ofthe jetpipe pressure, and if the only control of the jet pipe pressure relieson a fixed orifice, whether it be single or a series, then any decreasein the system (inlet) pressure will result in adecrease in jet pipepressure with a resultant loss of dynamic performance. A similar loss ofperformance could result from pressure losses caused by a correspondingincrease in fluid viscosity due to a fall in fluid temperature below thedesign temperature. To ensure that the valves of the present inventionfunction well in universal applications, incorporation of themodification shown in FIG. 12 into the valve shown in either FIG. 1 orFIG. 6 will provide an automatic temperature and pressure compensatedpressure reducer arrangement, which will provide a relatively constantoutlet pressure regardless of fluctuations in the pressure andtemperature of the inlet fluid.

The arrangement of FIG. 12 overcomes the limitations due to a fall injet pipe pressure by ensuring that the area of each orifice in thereducer varies inversely as the square root of the pressure change andincreases due to a fall in fluid temperature.

In FIG. 12 the modification is shown in an operating position. System(inlet) pressure in pressure port 24 flows through passage 84 to thebore 74 to act on the surface of the piston 73, which displaces the disc79 in the chamber 78 against the action of the coil spring 77. Fluidpressure downstream of the hydraulic jet motor is taken from the annularchamber 33 (FIG. 3) and 33' (FIG. 7) through passage 82 to the inletport 81 in the sleeve 69. Fluid flows through the annular chambers 89 inthe compensating spool 71 and the diametrically opposed ports in thesleeve to the outlet port 83. Displacement of the piston 73 istransmitted to the spool 71 through the aluminum rod 72 and results inthe edges of the annular chamber 89 intersecting the edges of ports 80,thus providing variable area orifices which regulate the pressure offluid flowing to the jet nozzle 110.

The spring rate of the coil spring 77 determines the degree of openingof the variable area orifices with respect to fluctuations in inletpressure acting on the piston 73, so that a constant pressure ismaintained at the jet nozzle 110.

Fluid leakage from around the spool 71 fills the chamber 78, which isconnected to outlet chamber 39 (FIG. 1), and surrounds the aluminium rod72. The fluid flows through the orifices 85 and the orifices 87 to fillthe chamber 88 on either side of the flange 86, thus providing a dashpottype fluid damping arrangement which may be desirable in certainapplications.

For the purpose of description itis assumed that the pressure andtemperature compensating arrangement is shown in a neutral position inFIG. 12, with pressure and temperature within design limits which,taking the examples previously given, means that the system (inlet)pressure in bore 74 is 3,000 p.s.i., the pressure in inlet port 81 is2,600 p.s.i., this being reduced by the restriction formed by thechambers 89 on the spool and the ports 80 in the sleeve to a pressure of200 p.s.i. in the outlet port 83. A fall in system pressure in bore 74causes the piston 73 to be moved downwards in the bore 74 under theaction of the coil spring 77. This downward movement is transmitted tothe spool 71 through the aluminium rod 72 to uncover more of the area ofthe ports in the sleeve 69, thereby increasing the area of the variableorifices formed with the chambers 89 on the spool, thereby maintaining aconstant fluid pressure in the outlet port 83 regardless of the fall influid pressure in inlet port 81 caused by the fall in system (inlet)pressure.

The number of stages of reduction in the compensated reducer is suchthat when the spool 71 is in the neutral position the effective area ofeach orifice is greater than that of the jet pipe 95, so that the valvesability to operate in contaminated fluid is not impaired. Thereliability aspect is, of course, improved in the arrangement describedwhen the system (inlet) pressure falls. The opposite effect on thisaspect due to a rise in system pressure need not be considered, as allsound systems are fitted with a pressure relief valve.

A fall in the temperature of the fluid surrounding the aluminium rod 72causes contraction of the rod which is secured at its lower end to thepiston 73 and at its upper end to the spool 71. As the piston 73 isbalanced by the fluid pressure in the bore 74 and the coil spring 77,contraction of the rod 72 causes downward movement of the spool 71within the sleeve 69 to again in crease the area of the orifices formedbetween the ports 80 and the chambers 89, causing an increase inpressure in outlet port 83 to compensate for pressure losses in the jetpipe arrangement, due to the increased viscosity of the lowertemperature fluid.

From the outlet port 83 the fluid passes down the bore 90 of housing 91into the deflecting jet 95 to eject from the jet nozzle 110 onto asplitter disc, as previously described in relation to the valve shown inFIG. 1. However, by passing the fluid through the unit as shown in FIG.12, the upper static transfer jet 109 shown in FIG. 1 can be dispensedwith, thus reducing fluid leakage. Displacement of the spool in a valveincorporating this modification is accomplished in exactly the samemanner as that previously described by swinging the deflecting jet 95through rotation of torque tube 96 by a torque motor (not shown).

If the valve is to be operated in an environment subject to accelerationforces, especially if the acceleration forces act along the longitudinalaxis of the spool, it will be desirable to provide some means ofcompensating for these forces so that the spool position remainssensibly unaltered and the output load is unaffected. One means ofachieving this is shown in FIG. 13.

Acceleration in the direction of arrow M results in an accelerationforce on the spool 11 in the direction of arrow N, and is a product ofthe magnitude of acceleration and the spool mass. This force is balancedby a force in the direction of arrow P being a product of actuatingchamber differential pressure (Ap) and the area (A) of the end of thespool upon which the pressure acts. The differential pressure (Ap) iscreated by a jet pipe displacement of L sin a where L is the length fromthe pivot point 107 to the nozzle of the jet pipe and a is the angulardeflection of the jet pipe due to acceleration. The relationship betweenchamber differential pressure and jet pipe displacement is shown in thegraph of FIG. 14. The angular deflection a is determined by themagnitude of acceleration in the direction 'of arrow M acting throughthe centre of gravity 108 which is located above the pivot point 107,and results in movement of the centre of gravity 108 in the direction ofarrow to swing thedeflecting jet 95 about the pivot point 107. Relatingthis movement now to the valve of FIG. 1, more fluid will enterreceiving chamber 42 than receiving chamber 41, causing an increase influid pressure inactuating chamber 48, resulting in a force equivalentto up A acting on the spool in the direction of arrow P (FIG. 13) tobalance the acceleration force in the direction of arrow N, therebycompensating for acceleration forces and maintaining the spool in thedesired position.

If desired, a damping facility can be provided on movement of thedeflecting jet 95 by closing the gaps between the surfaces of theprojection 99 and the walls of the body 17 and the retainer 93 toprovide the necessary degree of viscous shear face.

FIG. shows a modified form of spool which will enable the valve of thepresent invention to be used as a vibration control valve. In thisapplication the jet nozzle is fixed, there being no need, therefore, foratorque tube or torque motor. A required programme of vibration isshaped on the edges 102 and 103 of two receiving chambers 104 and 105located one at each side of a splitter disc 101. As the spool 106 isrotated, by either of the fluid jet motor arrangements previouslydescribed, it will be forced to oscillate axially in order to maintain astate of pressure balance between the stationary jet pipe 100 and theactuating chamber pressures at either end of the spool. Theseoscillations result in fluid pressure being supplied alternately toports 18 and 19 from inlet port 24 (FIG. 1) and are reproduced, withinthe response capacity of the system under vibration, at the load.

Dependent upon the extent of the operating temperature range and withinthe space limitations of the valve, the simple aluminum rod 72 shown inFIG. 12 could be replaced by a compound bi-metal concentric tubeelement, so increasing the valve opening per unit change of temperature.

In certain applications where a large fluctuating exhaust line backpressure is unavoidable the jet pipe pressure could be maintained,within certain limits, at a constant level abovethe back pressure byinterposing a chamber'between the disc 79 and the piston 73 ofappropriate area difference for the application, the chamber beingconnected to the outlet port 83 to be pressurized at jet pipe pressure.

In the embodiments of the invention hereinbefore described andillustrated it will be seen that a fluid control valve is provided inwhich a proportion of waste first stage fluid input pressure isharnessed to induce continuous rotation of the spool and to supply powerto a servo-mechanism controlling displacement of the spool in the boreof the valve. The spool is rotated all the time that fluid pressure issupplied to the pressure port 24, regardless of whether the spool ispositioned to permit a flow through the valve or whether the spool ispositioned so as to shut off the flow. This continuous rotation preventssticking and sluggish operation of the spool due to the fluidcontamination, and also the onset of hydraulic lock, and means thereforethat the valve is capableof efficient operation in areas which havehitherto caused many problems in hydraulic systems, particularly in thenull position.

An important feature of the invention lies in the fact that noadditional power source is required to either continuously rotate thespool or to cause displacement of the spool.

Many applications exist for valves with this facility wherever sensitivecontrol is required in areas of relatively high fluid contamination andmay, for instance, form the first stage of a hydraulic amplifier.

The modification shown in FIG. 15 indicates another unique example ofthe advantages to be gained in a particular application using a servocontrolled spinning spool.

Another very important feature of a fluid control valve manufactured inaccordance with the invention is the ease and simplicity with whichfault-finding and maintenance can be achieved. For instance, bymanufacturing the caps 50 from a transparent material, a visual checkwill determine whether a fault in a hydraulic system is being caused bya malfunctioning valve. If the spool is stationary, removal of a cap 50will enable the spool to be withdrawn from the sleeve 49 for cleaning ofthe passages and especially the orifices 27 (FIG. 1) or 27 (FIG. 6). Thespool is then replaced in the sleeve and the cap 50 refitted. Theself-centering facility provided by the jet nozzle and splitter discarrangement means that no set-up procedures are necessary, and that thevalve is ready for immediate use.

The main difference between the valves of FIGS. 1 and 6 is that in FIG.6 the splitter disc 40 has been moved to a central position on the spoolas opposed to being located at one end, as shown in the valve of FIG. 1.The central position of the splitter disc shown in FIG. 6 is preferredfrom a manufacturing viewpoint, and also because of the fact that thedyanmic response of the valve is improved. From FIG. 6 it will be clearthat the spool is made up of three parts, this type of constructionbeing suitable also for the spool of FIG. 1.

Although several variations of the invention have been described andillustrated it is to be understood that various modifications can bemade within the scope of the appended claims. For instance, in the valveof FIG. 1 the orifices 27 may be machined one from each side of the head14. The fluid jet motor may be in the form of vanes on the spool ontowhich fluid is ejected to impart the necessary torque. The inner wallsof receiving chambers 41 and 42 may be vaned or otherwise formed toprovide additional torque to the spool. Depending upon the levels offluid contamination it may be possible in a particular installation todispense with either one of the torque producing means previouslydescribed, though in the case of the splitter disc arrangement this maymean the provision of alternative forces for displacing the spool in thebore of the sleeve.

I claim as my invention:

1. In a fluid control valve, the combination comprising a valve bodyhaving a bore therein closed at each end and fluid inlet and outletports communicating with the bore, a spool located in the bore, saidspool having annular chambers formed between a plurality of headsarranged so that the axial position of the spool controls the flow offluid through the valve, a chamber in the bore at each end of the spool,a fluid jet motor formed in one of the heads on the spool forcontinuously rotating the spool when pressurized fluid is supplied tothe inlet port comprising a plurality of orifices extending into the onehead from an end adjacent a fluid inlet chamber on the spool and definedin part by the one head, the orifices connecting with at least onechamber formed on the circumference of the one head, ajet pipe assemblyincluding a deflecting jet terminating in a longitudinally movable jetnozzle, the jet nozzle being in fluid communication with two annularreceiving chambers formed in a head on the spool and separated by asplitter disc, and passage means within the spool connecting each of theannular receiving chambers with a different one of the chambers at eachend of the spool.

2. The combination set forth in claim 1, wherein the fluid jet motor andthe annular receiving chambers are located in the same head on thespool.

3. The combination set forth in claim 1, wherein the jet pipe assemblyincludes a static transfer jet.

4. The combination set forth in claim 1, wherein the jet pipe assemblyis supplied with pressurized fluid from downstream of the fluid jetmotor.

5. The combination set forth in claim 4, wherein a pressure reducer isinstalled between the fluid jet motor and the jet pipe assembly.

6. The combination set forth in claim 5, wherein the pressure reducercomprises a frustoconical unit having a plurality of chambers formedaround its circumference, an orifice connecting the upstream end of theunit to an inlet chamber being one of the plurality of chambers, anorifice in walls between the chambers with the exception of the wallbetween the inlet chamber and an adjacent outlet chamber being also oneof the pulurality of chambers, and an orifice connecting the outletchamber to the downstream end of the unit.

7. The combination set forth in claim 1, wherein the chamber at each endof the spool is bounded in part by a transparent cap.

8. A fluid control valve having a body, a sleeve fixedly secured in thebody and a spool located in a bore in the sleeve, a chamber in thesleeve at each end of the spool, inlet and outlet ports in the bodycommunicating with ports in the sleeve, annular chambers formed betweena plurality of heads on the spool, the heads being arranged so that theaxial position of the spool controls the flow of'fluid through thevalve, a fluid jet motor formed in one of the heads on the spool forcontinuously rotating the spool when pressurized fluid is supplied tothe inlet port, and means for varying the fluid pressure being suppliedto the chamber at each end of the spool, said fluid jet motor comprisinga plurality of orifices extending intothe one head from the end adjacenta fluid inlet chamber on the spool, and defined in part by the one head,the orifices connecting with at least one chamber formed on thecircumference of the one head.

1. In a fluid control valve, the combination comprising a valve bodyhaving a bore therein closed at each end and fluid inlet and outletports communicating with the bore, a spool located in the bore, saidspool having annular chambers formed between a plurality of headsarranged so that the axial position of the spool controls the flow offluid through the valve, a chamber in the bore at each end of the spool,a fluid jet motor formed in one of the heads on the spool forcontinuously rotating the spool when pressurized fluid is supplied tothe inlet port comprising a plurality of orifices extending into the onehead from an end adjacent a fluid inlet chamber on the spool and definedin part by the one head, the orifices connecting with at least onechamber formed on the circumference of the one head, a jet pipe assemblyincluding a deflecting jet terminating in a longitudinally movable jetnozzle, the jet nozzle being in fluid communication with two annularreceiving chambers formed in a head on the spool and separated by asplitter disc, and passage means within the spool connecting each of theannular receiving chambers With a different one of the chambers at eachend of the spool.
 2. The combination set forth in claim 1, wherein thefluid jet motor and the annular receiving chambers are located in thesame head on the spool.
 3. The combination set forth in claim 1, whereinthe jet pipe assembly includes a static transfer jet.
 4. The combinationset forth in claim 1, wherein the jet pipe assembly is supplied withpressurized fluid from downstream of the fluid jet motor.
 5. Thecombination set forth in claim 4, wherein a pressure reducer isinstalled between the fluid jet motor and the jet pipe assembly.
 6. Thecombination set forth in claim 5, wherein the pressure reducer comprisesa frustoconical unit having a plurality of chambers formed around itscircumference, an orifice connecting the upstream end of the unit to aninlet chamber being one of the plurality of chambers, an orifice inwalls between the chambers with the exception of the wall between theinlet chamber and an adjacent outlet chamber being also one of thepulurality of chambers, and an orifice connecting the outlet chamber tothe downstream end of the unit.
 7. The combination set forth in claim 1,wherein the chamber at each end of the spool is bounded in part by atransparent cap.
 8. A fluid control valve having a body, a sleevefixedly secured in the body and a spool located in a bore in the sleeve,a chamber in the sleeve at each end of the spool, inlet and outlet portsin the body communicating with ports in the sleeve, annular chambersformed between a plurality of heads on the spool, the heads beingarranged so that the axial position of the spool controls the flow offluid through the valve, a fluid jet motor formed in one of the heads onthe spool for continuously rotating the spool when pressurized fluid issupplied to the inlet port, and means for varying the fluid pressurebeing supplied to the chamber at each end of the spool, said fluid jetmotor comprising a plurality of orifices extending into the one headfrom the end adjacent a fluid inlet chamber on the spool, and defined inpart by the one head, the orifices connecting with at least one chamberformed on the circumference of the one head.